feat: init release backstage plugin

[hoangndst]

1. Does this PR affect any open issues?(Y/N) and add issue references (e.g. "fix #123", "re #123".):

• N
• Y

re #3

2. What is the scope of this PR (e.g. component or file name):

• .changeset/bumpy-rules-scream.md: Added a changeset file to document the initial release of the Backstage plugin for Kusion.
• .github/workflows/release.yml: Added caching for node_modules and the global Yarn cache in the GitHub Actions workflow to reduce build times. This includes steps to cache node_modules, find the global Yarn cache location, and cache the global Yarn cache. [1] [2]

3. Provide a description of the PR(e.g. more details, effects, motivations or doc link):

This pull request introduces the initial release of the Backstage plugin for Kusion and optimizes the GitHub Actions workflow by adding caching for node_modules and the global Yarn cache. These changes aim to improve the plugin's functionality and enhance CI/CD efficiency.

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Other

4. Are there any breaking changes?(Y/N) and describe the breaking changes(e.g. more details, motivations or doc link):

• N
• Y

5. Are there test cases for these changes?(Y/N) select and add more details, references or doc links:

• Unit test
• Integration test
• Benchmark (add benchmark stats below)
• Manual test (add detailed scripts or steps below)
• Other

6. Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None